Certain carbonaceous products of sugar fermentation are seen as replacements for petroleum-derived materials for use as feedstocks for the manufacture of carbon-containing chemicals. One such product is MAS.
SA can be produced by microorganisms using fermentable carbon sources such as sugars as starting materials. However, most commercially viable, succinate producing microorganisms described in the literature neutralize the fermentation broth to maintain an appropriate pH for maximum growth, conversion and productivity. Typically, the pH of the fermentation broth is maintained at or near a pH of 7 by introduction of ammonium hydroxide into the broth, thereby converting the SA to DAS.
Alternatively, the pH of the fermentation broth can be maintained at a selected value by introduction of sodium, potassium, or magnesium bases or mixtures thereof, including mixtures with ammonium bases. The addition of bases causes the SA to convert to other salts of SA. Other bases may include K+, Na+ and Mg+2, for example.
Kushiki (Japanese Published Patent Application, Publication No. 2005-139156) discloses a method of obtaining MAS from an aqueous solution of DAS that could be obtained from a fermentation broth to which an ammonium salt is added as a counter ion. Specifically, MAS is crystallized from an aqueous solution of DAS by adding acetic acid to the solution to adjust the pH of the solution to a value between 4.6 and 6.3, causing impure MAS to crystallize from the solution.
Masuda (Japanese Unexamined Application Publication P2007-254354, Oct. 4, 2007) describes partial deammoniation of dilute aqueous solutions of “ammonium succinate” of the formula H4NOOCCH2CH2COONH4. From the molecular formula disclosed, it can be seen that “ammonium succinate” is diammonium succinate. Masuda removes water and ammonia by heating solutions of the ammonium succinate to yield a solid SA-based composition containing, in addition to ammonium succinate, at least one of monoammonium succinate, succinic acid, monoamide succinate, succinimide, succinamide or ester succinate. Thus, it can be inferred that like Kushiki, Masuda discloses a process that results in production of impure MAS. The processes of both Kushiki and Masuda lead to materials that need to be subjected to various purification regimes to produce high purity MAS.
It would be desirable to have a process for the direct production of substantially pure MAS from a DAS, MAS, and/or SA-containing fermentation broth.